Power-operated amalgamator



Aug. 15, 1939. c. P. RUSSELL 2,159,317

POWER OPERATED AMALGAMATOR Filed Sept. 29, 1958 grwwvroz Cr/ 1 1 usse// Patented Aug. 15, 1939 L UNITED STATES PATENT OFFIQE POWER-OPERATED AMALGAMATOR,

, Carl P. Russell, Annapolis, Md. Application September 29, 1938, Serial No. 232,460

6' Claims;

This invention relates to power-operated mixing devices of the agitating type, wherein the materials are mixed by hurling them to and fro, or otherwise whipping them together by impact,

within a closed shiftable chamber.

My invention is especially concerned with a device of the above type, designed particularly for use in forming amalgams of, say, dental alloy and mercury, to provide fillings in the art of dentistry; and preferably the device isdesigned to be actuated, either directly or indirectly by the motor of a conventional dental engine.

I am aware of prior proposals to substitute a machine-type amalgamator for the mortar and pestle commonly used by dentists in mixing materials for tooth fillings, but to my knowledge none of such machines has attained commercial success, chiefly because each has had one or more of the following faults:

(1) Excessive vibration and noise.

(2) Lack of facility of operation and ease of handling.

(3) Improper proportioning of parts to effect proper and rapid amalgamation.

(4) Too expensive.

(5) Where designed for attachment to the conventional and relatively costly hand-piece of a dental engine, damages and shortens thelife of the hand-piece.

It is the primary object of the present invention to devise an improved amalgamator having none of the foregoing faults, defects or disadvantages. Otherwise stated, it is the principal object of my invention to produce a simple, com- 1 pact and inexpensive amalgamating machine having high efficiency and other desirable operating characteristics so that it will find wide acceptance and fill a long-felt need in the trade.

Individual or subordinate objects of the pres- 4u. ent invention are expressed in-the following discussion.

By properly designing the agitating cup with respect to the speed and length of stroke in the reciprocation of said cup'the cup depth prefer- 45. ably being slightly greater than the stroke length when the device is to be attached to modern conventional dental engines-I have been able to obtain thorough amalgamation of dental alloy and mercury, easily, within a time period of fifteen seconds.

By aligning the agitating rod that carries the cup with a rotary shaft that is to be connected to the power source, I have been able to produce a device that is compact and neat in appearance ;and that at the same time has no partstending to-set up torque productive of twisting or wobbling effects when power is applied.

Through the provision of a simple and compact unit for converting rotary movement to that of reciprocation, and the use of one or more thrust bearings and/or an extensible driving shaft, I have succeeded in substantially eliminating vibration and noise and in preventing transmission of shock from the amalgamator tothe conventional dental hand-piece or other mechanism utilized as a power source. l

The foregoing and further objects and advantages of the invention will appear clearly from a study of the following detailed description when taken in conjunction with the accompanying drawing and the appended claims. In the drawing:

Figure .1 is a view, approximately to scale, of a section taken centrally and longitudinally through the complete assembled machine of the present invention in its preferred form.

Figure 2 represents a cross-section taken on the plane of line 2-2 in Figure 1.

Figure 3 is another cross-section, taken on the plane of line 33, Figure 1.

Figure 4 is a view showing development of the cam groove on the interior of the hollow cam member.

Figure 5 is a detail view, in side elevation, of the agitating rod and. its follower-pin.

Figure 6 is a detail view of a modified form of rotary shaft that may be used in the machine of Figures 1 to 5.

With continued reference to the drawing, wherein like reference characters are employed to designate like parts, the assembly of Figure 1 comprises essentially a two-part body B, a rotary drive spindle S, an agitating rod R carrying a cup C, and a cam member M intercoupling the spindle and. the rod.

The two parts, I and 8, of the body B are rigidly but detachably joined, as by threads H), to form a barrel. The part 1 serves as a guide for the rod R and a housing for the member M; and preferably has several fiat sides as shown and is designed to rest in the palm of the hand. The part 8 is adapted to receive the nose of a conventional hand-piece of a dental engine and has a slot ll designed to register with the usual 10- cating and stop pin (not shown) providedon such a hand-piece. When the pin and slot are in registry the free end l2 of the spindle S will be surrounded by the usual driving sleeve (not shown) of the hand-piece and may be quickly coupled to the latter in the same manner that the sleeve is caused to grip conventional dental tools such as drills, polishers and the like.

The upper end of the barrel part 8 is annularly recessed to receive the outer race of a conventional thrust bearing l3 of the anti-frictional type. The inner race of this bearing snugly fits the body of spindle S, and the latter has an integral collar I4 contacting the top side of said inner race, whereby the spindle is fixed against movement axially of the body B in the direction of the hand-piece. Beyond the collar the spindle has an integral screw-threaded plug l5 designed for reception in the complementally threaded bottom of the cup-shaped cam member M, a washer l6 being disposed between said bottom and said collar.

The cam member has a. cylindrical wall I! of less diameter than the surrounding wall of part I, and at its upper end is recessed annularly, as shown, to receive the inner race of a conventional radial and thrust bearing l8 of the anti-frictional type. The outer race of this bearing snugly fits a shouldered internal portion of. the part 1. Above this bearing the part 1 is provided with a liner 20 of brass or any suitable bearing material for guidance of the reciprocating rod R there being a minimum working clearance between the rod and its complemental guideand preferably a lubricating and vibration deadening washer 2| of felt or the like is mounted at the upper end of the liner.

The guided stem or body 22 of the rod R is square or otherwise shaped to prevent its rotation, and may be provided with oil-distributing grooves 23 (Figure 5) on its flat sides. Its upper end is tightly secured in a metal cap 24 which in turn is rigidly united to the cup C, the latter being formed of phenolic condensate or any other material that will not combine chemically with or adhere to the materials to be amalgamated.

The cup comprises the part 25, permanently joined to the rod; and a knurled, readily detachable cap 26, the two parts cooperating when assembled to form an amalgamating or agitating chamber 21. A tight annular seal is effected between the two parts by making the internally threaded cylindrical wall of part 26 shorter than the externally threaded wall of the part 25, as shown.

The rod R is, as aforestated, axially. aligned with spindle S and at its lower end is provided with a transverse follower-pin assembly comprising a pin 28 having at one end an integral head 30 and at its other end a rotatable bushing 3| designed to fit with running clearance within a cam track in the form of a groove 32 out or otherwise provided on the interior surface of the cam member M, and a spacer 33 (which also may serve as a pin retainer) disposed between said bushing and the adjacent flat side of the rod. All of these parts may be made of hardened steel, or of any material that will resist wear and preclude development of excessive friction.

The groove 32 forms an endless cam track that is of uniform size and shape throughout its length, and that is inclined in Figure 1 with respect to the horizontal so that each revolution of the cam member M by the spindle S will cause the pin assembly-and therefore the rod R,to make one complete reciprocation, the length of stroke depending upon the degree of track inclination. A development of the track is shown in Figure 4.

Except for the existence of the groove 32, the

interior surface of, the wall llis perfectly, cylina drical and smooth, and the working parts are so dimensioned that the illustrated rounded surface of the pin head 32 rides on this smooth surface while the opposite end of the pin rides on the bottom of the groove. The parts thus are steadied against lateral movement that might tend to create vibration, and/or excessive friction between the rod body 22 and the liner 20. The bushing 3| is provided to minimize friction and wear at the cam groove. It partakes of both translational and rotational movement.

The motion converting mechanism may be reyersed to the extent of securing the pin to the spindle for rotation and connecting the cam member to the rod for reciprocation. The illustrated arrangement, however, is preferred.

The stroke of the rod R is desirably short, and the depth of the chamber 21 is slightly diiferent from (preferably slightly greater than) the stroke length, so that all of. the materials to be mixed are definitely brought into violent impact with the chamber end walls continuously during operation, rather than too gently floated to and fro without positive batting action and sudden directional changes. This feature is important in obtaining a thorough and rapid whipping of the materials into a suitable amalgam.

The modified form of drive shown in Figure 6 is designed to afford absolute assurance that internal vibrations and shocks will not be transmitted to the somewhat delicate and relatively expensive hand-piece of the dental engine which supplies, indirectly through said hand-piece, amalgamating power from its electric motor. In this form the spindle S is made with its body in the form of a sleeve 35 which rather loosely receives one end of the separate outer stem 36. The received end of the stem carries a cross-pin 38 that projects freely into an elongated slot 31 of the body 35, so that the parts 35, 3'6 are coupled for rotation while permitted to partake of slight axial movement independently of each other. This feature is not of great importance except in the event of excessive wear, caused by negligence, in the other working parts, or in the event that the anti-frictional thrust bearings are omitted from the barrel in the assembly of Figure 1. l

Any suitable oil-hole and wick device or othe satisfactory lubricating means of known type may be provided for maintaining the working parts-within the barrel in a proper state of lubrication.

The operation of my improved amalgamator is thought to be obvious from the foregoing description. To summarize, the cap of the cup C is removed and proper small quantities of materials added to the chamber 21, after which the cap is tightly replaced. If the machine has no permanent anchorage and drive means, it is attached to the dental engine handpiece. Power then is applied, rotation of the spindle causing rapid reciprocation of the rod R in short strokes, with consequent violent and effective agitation of the materials to form an amalgam that is suitable for use after squeezing any excess mercury therefrom.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A portable amalgamating device of the character described, comprising a housing of such size and shape as to fit conveniently within the hand of an operator, mechanism within said housing for converting rotary motion to reciprocating motion, a rotary shaft projecting into connection with said mechanism from one end of the housing, a reciprocating rod aligned with said shaft and projecting directly into connection with said mechanism from the other end of said housing, and means carried by said rod and forming an agitating chamber externally of said housing,

2. A power-operable amalgamator of the character described, comprising an elongated housing structure, a rod slidable axially in and guided non-rotatably by one end of said structure, a rotary element carried by said structure in alignment with but spaced axially from said rod, means within said housing and between said element and said rod for converting rotation of the former into reciprocation of the latter, means on said housing adapting it for attachment nonrotatably to the handpiece of a dental engine, and means carried on said rod externally of said housing structure and designed to form an agitating chamber.

3. In the device set forth in claim 2, said converting means comprising a rotary cam member connected to said drive element and having an internal cylindrical surface aligned with said rod, said member including an endless groove in said internal surface, and a follower carried by said rod and designed to travel in said groove.

4. In the combination set forth in claim 2, at least one radial and thrust bearing of the antifrictional type fitted within said housing to center said converting mechanism and check end thrust in the direction of the rotary element.

5. In the apparatus defined in claim 2, said chamber having a substantially uniform depth dimension that is small and that slightly exceeds the stroke dimension of the reciprocating element.

6. A machine of the character described, designed for connection to and actuation by the hand-piece of a dental engine, comprising a housing designed to telescope at one end with the hand-piece, a reciprocating element extending into the other end of said housing, a rotatable shaft assembly within the housing, and means between said element and said shaft assembly to convert rotation of the latter into reciprocation of the former, said shaft assembly comprising two aligned parts intercoupled. for unitary rotation and to permit a substantial movement axially relative to each other, one of said parts designed to be driven by the handpiece and the other being connected to said converting means.

CARL P. RUSSELL. 

